A. Field of the Invention
This invention relates to the field of art of voltage controlled oscillators.
B. Prior Art
Variable oscillators have been known in which the frequency of the oscillator may be readily varied to meet the requirements of an application. Such applications have included frequency modulation for telemetry and data communications, triggered generators for variable frequency power inverters and phase-locked loop systems. Such applications have generally required a large ratio between maximum and minimum available frequency and thus variable oscillators have not used resonant circuit elements but have instead operated on the relaxation principle. A capacitor has been charged to a predetermined level at which its discharge is initiated and a new charging cycle begun. In such variable oscillators, the frequency has been varied over considerable range by varying the charging rate or the discharge threshold level or both. However, some prior variable oscillators have left much to be desired in their requirement of auxiliary circuits in order to start the oscillator. A further deficiency has been that during the time of transition of the state of the oscillator the charging current source has been simultaneously connected to both sides of the capacitor causing objectionable supply current spikes as well as asymmetry of the two portions of the oscillator cycle.